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Monday, 22 December 2008

Serendipitous timing has allowed researchers in Canada to capture the brain activity of a woman experiencing a spontaneous sense of someone else being in the room with her, when really she was alone.

This feeling of sensed presence is rather common. For example, more than half of patients who suffer a head injury without loss of consciousness go on to experience a sensed presence during the subsequent year. It's also common among people with temporal lobe epilepsy. Curiously, the presence is perceived to be a person of the opposite sex on more than ninety per cent of occasions. Patients usually describe the feeling as distressing and in some cases it can trigger depression. Others interpret the sensation as a religious experience.

Michael Persinger's research team have been interested for many years now in understanding the neural correlates of a sensed presence and other unusual perceptual experiences. They've argued a sensed presence is associated with aberrant electrical activity in the temporal lobes of the brain - that's why people with temporal lobe epilepsy report the feeling so often. Among other supportive findings, Persinger's team have also documented aberrant electrical activity occurring in the temporal lobe of an expert meditator while she reported a powerful sense of presence.

In the current study, a woman who'd two years' previously suffered head injuries in a car crash, was undergoing routine neuropsychological tests, which included having the electrical activity of her brain recorded by electroencephalogram (EEG).

This woman had been known to experience incidents of a sensed presence since her injury, and in this case, somewhat serendipitously, she experienced the phenomenon while her brain activity was being recorded.

It began with a feeling of an electric shock in her right hand, was followed by her arms and hands feeling icy cold, then vibrations went through her body, before she experienced the feeling that a man was in the room with her, even though she was actually alone.

A look at the EEG scans showed that a burst of electrical activity, similar to that observed in an epileptic seizure, occurred in her left temporal lobe at approximately the same time that she reported the sensed presence on her right-hand side.

"Although over the last 20 years we have assessed hundreds of patients who reported the emergence of a sensed presence ... this is the first time the reports of a strong ‘sensed presence’ and related sensations occurred ‘spontaneously’ while our screening electroencephalographic measurements were in progress," said Persinger and his coauthor Sandra Tiller.
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